Cosmetic use of skin cell autophagy activators

ABSTRACT

The object of the invention is the use in a cosmetic composition of an effective amount of at least one cutaneous cell autophagy activator as a cosmetic active ingredient. The invention also relates to cosmetic compositions that include at least one cutaneous cell autophagy activator as a cosmetic active ingredient 5 and a cosmetic process for detoxifying skin and/or for preventing or combating cutaneous aging.

This application is a division of copending application Ser. No.13/133,046 filed on Jun. 6, 2011; which is the 35 U.S.C. 371 nationalstage of International application PCT/FR2009/052410 filed on Dec. 4,2009; which claims priority to French application 0858308 filed on Dec.5, 2008. The entire contents of each of the above-identifiedapplications are hereby incorporated by reference.

This invention relates to the use—in a cosmetic composition—of anactivator of the autophagy of cells of the skin as a cosmetic activeingredient.

The object of the invention is also cosmetic compositions that compriseat least one activator of the autophagy of cells of the skin as acosmetic active ingredient as well as a cosmetic process for detoxifyingthe skin and/or for preventing or combating cutaneous aging, comprisingthe topical application of such compositions on the skin.

The skin, organ in contact with the environment, is constantly subjectedto damage, both from the outside and from the inside, which threatensits balance and alters its appearance.

It is known, for example, that excessive exposure to ultraviolet rays(UV) is reflected by various cutaneous manifestations, such as actinicerythemas, solar elastosis, or else the premature appearance of theeffects of cutaneous aging: the skin becomes loose, deeply wrinkled,rough, dry, sprinkled with hypopigmented or hyperpigmented spots anddilated vessels. These manifestations, which reflect profound structuralchanges in the cutaneous tissue, are unsightly and ugly, and many peoplehave a tendency to want to smooth them out.

This is why the objective of this invention is to propose an effectivemeans for protecting the skin against damage that can alter its properoperation and its appearance and for combating the manifestations thatfollow therefrom.

To respond to this, this invention proposes using at least one activatorof the autophagy of cells of the skin, in particular keratinocytes andfibroblasts, as a cosmetic active ingredient in a cosmetic composition.

Actually, the use of at least one cutaneous cell autophagy activatormakes it possible to combat the accumulation of deleterious molecules inthe cutaneous cells that are produced in the case of stress and thus tocombat the manifestations that follow therefrom.

In particular, the purpose of the invention is the use in a cosmeticcomposition of at least one activator of the autophagy of cells of theskin, in particular keratinocytes and/or fibroblasts, as an activeingredient, for detoxifying the cutaneous cells, combating the aging ofthe skin, restructuring the skin, hydrating and protecting the hornylayer, increasing cellular renewal, protecting the cells from theharmful effects of UVA and UVB radiation, and limiting the inflammationphenomena.

Preferably, the purpose of the invention is the use in a cosmeticcomposition of at least one activator of the autophagy of cells of theskin, as an active ingredient that is designed to detoxify the cells ofthe skin and/or to combat the cutaneous aging.

Advantageously, by increasing the autophagy mechanism in the cutaneouscells, the use according to the invention makes it possible to increasethe elimination of damaged molecules, to detoxify the skin, and to limitthe cutaneous aging.

Actually, under certain conditions, in particular with age andoverexposure to sun, the cells of the skin are no longer in a state toevacuate the molecules that are damaged by the radiation and the variousstresses. The cells are engorged with these damaged molecules and withfree radicals. The cosmetic use of cutaneous cell autophagy activatorsaccording to the invention makes it possible to limit this cellularengorgement and to remove therefrom the cells of deleterious and uselesselements that impede its optimal operation by accumulating.

The object of the invention is also a cosmetic composition for topicalapplication on the skin that comprises—in a physiologically acceptablemedium—an effective amount of at least one cutaneous cell autophagyactivator that is selected from among active ingredients that originatefrom Lithothamnium calcareum, Melilotus officinalis, Citrus limonum,Candida saitoana, Lens culinaris, Averrhoa carambola, Momordicacharantia, Yarrowia lipolytica and at least one cosmetic adjuvant.Preferably, the cutaneous cell autophagy activator is present in anamount that is between 0.1 and 15% by weight relative to the totalweight of the composition.

Finally, the invention also has as its object a cosmetic process fordetoxifying the skin and/or for preventing or combating cutaneous aging,comprising the topical application on the skin of a composition thatcomprises at least one activator of the autophagy of cells of the skin.

The invention is now described in detail.

The purpose of this invention is therefore the use in a cosmeticcomposition of an autophagy activator as a cosmetic active ingredient.

Autophagy is a mechanism for recycling and detoxifying cellularcomponents and organites. In particular, autophagy makes it possible toregulate, repair and eliminate proteins with a long service life in thecells, thus ensuring a control during differentiation and aging of humanskin.

On the cellular plane, the autophagy mechanism comprises four stages:initiation, formation of an initial vacuole, named autophagosome, whichsequesters the cytoplasmic material, the maturation of the autophagosomeinto a degradative vacuole, and fusion with the lysosome until thedegradation of the sequestered material is achieved.

According to a first aspect, a cutaneous cell autophagy activator thatis useful according to the invention can be an active ingredient thathas a stimulating activity of the expression of MAP-LC3(“microtubule-associated membrane protein,” membrane proteins combinedwith microtubules) and/or ATG5-12 (“autophagy-related genes,” genes ofautophagy) of cells of the skin.

Actually, the formation of the autophagosome, an essential stage in themechanism of the autophagy, involves two coupling systems: the complexATG5-12 and the MAP-LC3.

The first stage of the autophagy is the formation of a multi-membranestructure, called a phagophore, whose origin remains unknown. Thisstructure is extended to form the autophagosome that sequesters thecytoplasmic material. The autophagosome fuses with the lysosome, and itscontent is then degraded by the lysosomal enzymes. During the formationof the autophagosome, ATG proteins are engaged starting from cytoplasmand are combined temporarily with the autophagosomal membrane.

This process primarily involves three protein complexes: the PI(3)K ofClass III combined with the protein Beclin-1 and two coupling systems.The early event in the induction of the formation of the autophagosomeis the production of phosphatidyl inositol 3-phosphate by the complexBeclin-1-PI(3)K of Class III that makes possible the engagement of thefirst coupling system ATG12-ATG5, also referred to as ATG5-12. Thelatter, in turn, makes possible the coupling of the phosphatidylethanolamine (PE) with the protein MAP-LC3 for forming the conjugateMAP-LC3-PE, which is then engaged with the autophagosomal membrane.

The ATG genes are therefore involved in the formation of theautophagosome, and ATG5-12 is a precursor of the coupling of MAP-LC3 andphosphatidyl ethanolamine (PE).

The MAP-LC3 are proteins of 15 kDa that are present in mammals They areused at the time of the formation of membranes of the autophagosomes.There are two forms of them: a cystolic form, the LC3-I, and a form thatis linked to the membrane LC3-II.

In a first step, the MAP-LC3 are cleaved directly after their synthesis,at their C-terminal part so as to provide the LC3-I cystolic form.During the autophagy, LC3-I is converted into LC3-II, and the proteinsare combined with autophagic vacuoles.

Thus, the use of an active ingredient that has a stimulating activity ofthe expression of MAP-LC3 and/or ATG5-12 of the cells of the skin makesit possible to stimulate the formation of the autophagosome andtherefore to stimulate the autophagy of cells of the skin.

According to a second aspect, an activator of the autophagy of cutaneouscells that is useful according to the invention can be an activeingredient that inhibits the activation of phosphorylated mTOR.

The complex mTOR (“mammalian Target Of Rapamycin” or target of therapamycin of mammals) is a molecule that is involved in the initiationof the formation of the autophagosome. It plays a role of sensor of theATP and amino acids regulating the balance between the availability ofnutrients and cellular growth.

When the amount of nutrients is sufficient, mTOR is phosphorylated onserine 2448 and transmits a positive signal that activates the cellulargrowth and inhibits autophagy.

If this is not the case, i.e., under conditions of nutritionaldeprivation or starvation, this phosphorylation disappears in favor of aphosphorylation of threonine 2446, which makes it possible to lift theinhibition of autophagy.

The autophagy mechanism is therefore initiated when there isdephosphorylation of mTOR on serine 2448.

Thus, the cosmetic use of an active ingredient that inhibits theactivity of mTOR in the cells of the skin makes it possible to promotethe initiation of autophagy, to mobilize the formation ofautophagosomes, and therefore to stimulate the autophagy of cells of theskin.

According to a final aspect, a stimulator of the autophagy activity ofthe cutaneous cells that is useful according to the invention can be anactive ingredient that has a stimulating activity of the expression ofthe protein p53, the AMPK, and/or DRAM.

The protein p53 is a major protein of stress, capable of, in particular:

-   -   Activating the protein DRAM (“Damage Regulated Autophagy        Modulator,” modulator of damage regulated by autophagy), a        protein that is directly involved in the initiation of the        autophagy mechanism, and    -   Inhibiting mTOR by means of the activation of a protein kinase,        AMPK.

The activation of DRAM and/or AMPK, either directly or by means of p53,therefore makes it possible to stimulate autophagy.

Thus, the cosmetic use of an active ingredient that has a stimulatingactivity of the expression of the phosphorylated protein p53, DRAMand/or AMPK of the cells of the skin makes it possible to promote theinitiation of autophagy, to mobilize the formation of theautophagosomes, and therefore to stimulate the autophagy of cells of theskin.

The cellular consequence of an activation of the autophagy mechanism byan active ingredient that has a stimulating activity of the expressionof MAP-LC3, ATG5-12, the phosphorylated protein p53, DRAM and/or AMPKand/or that has an inhibiting activity of phosphorylated mTOR is abetter detoxification of the cells, i.e., a reduction of the reactiveoxidized radicals and degenerated macromolecules that are locked in thecutaneous cells. Preferably, the stimulator of the cutaneous cellautophagic activity that is useful according to the invention is anactive ingredient that originates from at least one plant, one algae orone yeast.

In a preferred way, the autophagy activator is an active ingredient thatoriginates from at least one algae of the Lithothamnium calcareum type,or a plant that is selected from among Melilotus officinalis, Citruslimonum, Lens culinaris, Averrhoa carambola, Momordica charantia, or ayeast that is selected from among Candida saitoana and Yarrowialipolytica.

According to one aspect of the invention, the cutaneous cell autophagyactivator can be selected by a test that is executed on cultures ofcutaneous cells that comprise the following stages:

-   -   Cultivation of cutaneous cells, keratinocytes or fibroblasts,        within a suitable culture medium,    -   Removal of the culture medium and replacement by a culture        medium that comprises a stressing agent that induces a nutritive        and/or oxidative stress,    -   Addition of an active ingredient that originates from a plant,        algae or yeast that is to be tested within the culture medium,    -   Removal of the oxidizing agent and replacement of the culture        medium by a culture medium that comprises the active ingredient,        and    -   Analysis of the expression of MAP-LC3, ATG5-12, phosphorylated        mTOR, phosphorylated protein p53, the expression of the protein        DRAM and/or AMPK by said cells, and comparison of the results        with those that are obtained on cultures of cutaneous cells that        are not treated with the extract to be tested.

If an increase of the expression of MAP-LC3, ATG5-12, the phosphorylatedprotein p53, the protein DRAM and/or AMPK, and/or a reduction ofphosphorylated mTOR is noted, then the tested active ingredient can beused in a cosmetic composition as an activator of the autophagy of cellsof the skin.

To illustrate the invention, several active ingredients have been testedfor studying their capacity to increase the autophagy of cutaneouscells.

First, it was verified that the induction of stress at the cells of theskin duly produced an increase of the autophagy.

Next, the level of autophagy of young and old cells, subjected to thesame oxidative and nutritive stresses, was compared.

Finally, active ingredients were selected by the execution of the testprocess according to the invention.

1/Visualization of the Cutaneous Cell Autophagy After Nutritive Stress

The protocol that is executed consists in subjecting HaCaT-typekeratinocyte cultures or normal human keratinocytes to nutritive stress,i.e., to an absence of growth factors, for a certain period, and toevaluate the expression of several autophagy markers during the cellularrecovery.

The protocol is as follows:

-   -   Cultures of cells of the skin for 24 hours in the complete        culture medium (with growth factors),    -   Removal of the complete culture medium and replacement by a        non-nutritive culture medium (without a growth factor). The        cells are cultivated for some time (from 0.5 hour to 24 hours)        in a state of nutritive stress,    -   After these cultivation times in a state of nutritive stress,        removal of the non-nutritive culture medium and replacement by        the complete culture medium, and finally    -   Evaluation of the autophagy state of cutaneous cells by        evaluation of the expression of MAP-LC3, the complex ATG5-12,        phosphorylated mTOR, phosphorylated p53, DRAM and phosphorylated        AMPK after cellular recovery.

1.1/Evaluation of the Expression of MAP-LC3 After Nutritive Stress

It is possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of the protein MAP-LC3 by immunofluorescentmarking.

The expression of MAP-LC3 was evaluated on cultures of cutaneous cellsof lines HaCaT and on normal human keratinocytes after different contacttimes of the nutritive stress. With the immunomarking results beingqualitative, several levels of expression of MAP-LC3 were defined:

Very low detection of immunoreactivity − Low detection ofimmunoreactivity ± Medium detection of immunoreactivity + Strongdetection of immunoreactivity ++

The results that are obtained are presented in the table below:

Cultivation Times in a State Expression of of Nutritive Stress (Hours)MAP-LC3 0 − 0.5 − 1 − 2 + 3 + 4 ++ 8 + 24 −

During the cultivation of the HaCaT keratinocytes in the state ofnutritive stress, the clear appearance of a point marking MAP-LC3 at thecytoplasm of cells is observed. This marking reflects the formation ofautophagosomes in the keratinocytes subjected to nutritive stress.

This marking can be observed upon two hours of starvation and reaches amaximum after four hours of starvation.

These nutritive stress conditions therefore make it possible to inducethe formation of autophagosomes and consequently an autophagy,visualized by the expression of MAP-LC3.

1.2/Evaluation of the Expression of the Complex ATG5-12 After NutritiveStress

It is also possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of the complex ATG5-12 by immunofluorescentmarking.

The evaluation of the expression of the complex ATG5-12 was executed oncultures of cutaneous cells of lines HaCaT and on normal humankeratinocytes after different times of cultivation in a state ofnutritive stress. With the immunomarking results being qualitative,several levels of expression of ATG5-12 were defined:

Very low detection of immunoreactivity − Low detection ofimmunoreactivity ± Medium detection of immunoreactivity + Strongdetection of immunoreactivity ++ Very strong detection ofimmunoreactivity +++

The results that are obtained are presented in the table below:

Cultivation Times in a State Expression of of Nutritive Stress (Hours)ATG5-12 0 ± 1 ++ 2 ++ 3 ++ 4 +

During the cultivation of the HaCaT keratinocytes in a state ofnutritive stress, the clear appearance of a point marking ATG5-12 at thecytoplasm of cells is observed. This marking reflects the formation ofautophagosomes in the keratinocytes that are subjected to nutritivestress.

This marking can be observed upon one hour and up to three hours ofstarvation.

The nutritive stress conditions therefore make it possible to induce anautophagic-type phenomenon, visualized by the expression ATG5-12.

1.3/Evaluation of the Expression of Phosphorylated mTOR after NutritiveStress

It is also possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of mTOR that is phosphorylated by WesternBlott.

The evaluation of the expression of phosphorylated mTOR has beenevaluated on cultures of cutaneous cells of lines HaCaT and on normalhuman keratinocytes after different cultivation times in a state ofnutritive stress. The expression of phosphorylated mTOR is presented inthe table below in percentage relative to the control (without nutritivestress).

Cultivation Times in a State Expression of of Nutritive Stress (Hours)Phosphorylated mTOR (%) 0 100 2 118 4 122 8 78 12 64 24 58

This experiment showed a significant reduction of the phosphorylatedprotein mTOR that is visible upon eight hours of deprivation in thecultures of cutaneous cells subjected to starvation.

When the phosphorylated protein mTOR decreases, the inhibition of theautophagy is lifted.

The nutritive stress conditions therefore make it possible to induceautophagy on cultures of cutaneous cells, visualized by the reduction ofthe phosphorylated mTOR expression.

1.4/Evaluation of the Expression of Phosphorylated p53 after NutritiveStress

It is also possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of the phosphorylated protein p53 by WesternBlott.

The evaluation of the expression of the phosphorylated protein p53 wasevaluated on cultures of cutaneous cells of lines HaCaT and on normalhuman keratinocytes after different cultivation times in a state ofnutritive stress. The expression of phosphorylated p53 is presented inthe table below in percentage relative to the control (without nutritivestress).

Cultivation Times in a State Expression of of Nutritive Stress (Hours)Phosphorylated p53 (%) 0 100 0.5 140 1 170 1.5 168 2 161

This experiment showed a significant increase of the expression of thephosphorylated protein p53 that is visible upon one hour in cellcultures subjected to starvation.

The nutritive stress conditions therefore make it possible to induce anautophagic-type phenomenon on cultures of cutaneous cells, visualized bythe increase of the expression of the phosphorylated protein p53.

1.5/Evaluation of the Expression of the Protein DRAM After NutritiveStress

It is also possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of the protein DRAM, by Western Blott, oncultures of cutaneous cells of lines HaCaT and on normal humankeratinocytes after different cultivation times in a state of nutritivestress. The expression of DRAM is presented in the table below inpercentage relative to the control (without nutritive stress).

Expression of Cultivation Times in a State the Protein of NutritiveStress (Hours) DRAM (%) 0 100 0.5 260 1 220 1.5 330 2 95

This experiment showed a significant increase of the expression of theprotein DRAM after 0.5 hour of cultivation in a state of nutritivestress. The expression of the protein DRAM peaks after 1.5 hours ofcultivation in a state of nutritive stress. This coincides with thekinetics of expression of the protein p53 that reaches its maximum afterone hour of nutritive stress.

The nutritive stress conditions therefore make it possible to induce anautophagic-type phenomenon on cultures of cutaneous cells, visualized bythe increase of the expression of the protein DRAM.

1.6/Evaluation of the Expression of the Phosphorylated Protein AMPKAfter Nutritive Stress

It is also possible to evaluate the autophagy of cutaneous cells byvisualizing the expression of the phosphorylated protein AMPK, byWestern Blott, on cultures of cutaneous cells of lines HaCaT and onnormal human keratinocytes after different cultivation times in a stateof nutritive stress. The expression of DRAM is presented in the tablebelow in a percentage relative to the control (without nutritivestress).

Expression of Cultivation Times in a State Phosphorylated of NutritiveStress (Hours) AMPK (%) 0 98 0.5 155 1 170 1.5 172 2 130

This experiment showed that the expression of phosphorylated AMPK isincreased upon 0.5 hour of cultivation in a state of nutritive stressand peaks at 1.5 hours. This coincides with the kinetics of expressionof the protein p53 that reaches its maximum after one hour of nutritivestress.

The nutritive stress conditions therefore make it possible to induce anautophagic-type phenomenon on cultures of cutaneous cells, visualized bythe increase of the expression of the phosphorylated protein AMPK.

These studies have therefore made it possible to show that the autophagymechanism can be equally visualized on stressed cutaneous cell culturesby the evaluation of the expression of different proteins such asMAP-LC3, the complex ATG5-12, phosphorylated mTOR, the phosphorylatedprotein p53, the protein DRAM or the phosphorylated protein AMPK.

2/Visualization of the Autophagy of Cutaneous Cells After a Nutritiveand Oxidative Stress

The visualization of the autophagy is possible, as in the case of thenutritive stress, by the evaluation of different proteins such asMAP-LC3, the complex ATG5-12, the phosphorylated protein mTOR, thephosphorylated protein p53, the protein DRAM or the phosphorylatedprotein AMPK. In this experiment, the expression of the autophagy ofcutaneous cells was studied by analyzing the expression of MAP-LC3, thephosphorylated protein p53, and the protein DRAM in the stressedcutaneous cell cultures.

The protocol is as follows:

-   -   Cultivation of cells for 24 hours in a complete culture medium.    -   Removal of the culture medium and replacement with the        non-nutritive culture medium that contains the oxidizing agent        H₂O₂ for 3 hours (different doses of H₂O₂—125 μM and/or 250        μM—have been tested).    -   Removal of the oxidizing agent and the non-nutritive culture        medium, replacement by a complete culture medium without an        oxidizing agent.    -   Evaluation of the expression of MAP-LC3, the phosphorylated        protein p53, or the protein DRAM after cellular recovery.        Several recovery times have been selected (0.5 hour, 1 hour, 1.5        hours, or 2 hours of recovery).

2.1/Evaluation of the Expression MAP-LC3 After Nutritive and OxidativeStress

It is possible to evaluate the autophagy of stressed cutaneous cells byvisualizing the expression of the protein MAP-LC3 by immunofluorescentmarking.

The evaluation of the expression MAP-LC3 was analyzed under thesemoderate stress conditions (125 μM and 250 μM of hydrogen peroxide H₂O₂)on HaCaT keratinocyte cultures and on normal human keratinocytes. Withthe immunomarking results being qualitative, several levels ofexpression of ATG5-12 were defined:

Very low detection of immunoreactivity − Low detection ofimmunoreactivity ± Medium detection of immunoreactivity + Strongdetection of immunoreactivity ++ Very strong detection ofimmunoreactivity +++

The results that are obtained are presented in the table below:

Recovery Time (Hours) Expression of MAP-LC3 Without Stress 2 + H₂O₂, 125μM 0.5 ++ 1 ++ 1.5 +++ 2 ++ H₂O₂, 250 μM 0.5 ++ 1 +++ 1.5 ++ 2 +

For the 125 μM dose of oxidative stress, the point marking of MAP-LC3 atthe cytoplasm of cells is observed upon 0.5 hour of recovery, whichpeaks after 1.5 hours, and then is minimized from two hours of recovery.

For the 250 μM dose, it is noted that this marking appears upon 0.5hour, reaches a maximum at 1 hour, and is reduced upon 1.5 hours ofrecovery.

The nutritive and oxidative stress conditions therefore make it possibleto induce an autophagic-type phenomenon, visualized by the increase ofthe expression of MAP-LC3 in the cutaneous cells.

2.3/Evaluation of the Expression of the Phosphorylated Protein p53 AfterNutritive and Oxidative Stress

It is also possible to evaluate the autophagy of stressed cutaneouscells by visualizing the expression of the phosphorylated protein p53 byWestern Blott.

The evaluation of the expression of the phosphorylated protein p53 hastherefore been analyzed under these moderate stress conditions with 125μM of H₂O₂ on HaCaT keratinocyte cultures and on normal humankeratinocytes. The expression of phosphorylated p53 is presented in thetable below in percentage relative to the control (without stress).

Recovery Time Phosphorylated Expression (Hours) p53 (%) Without Stress 2100 H₂O₂, 125 μM 0.5 221 1 140 2 128

For the 125 μM dose of nutritive and oxidative stress, it is observedthat the marking of the phosphorylated protein p53 is at its maximumafter 0.5 hour of recovery, and then it is gradually minimized.

The oxidative stress conditions therefore make it possible to induce anautophagic-type phenomenon, visualized by the increase of the expressionof the phosphorylated protein p53.

2.4/Evaluation of the Expression of the Protein DRAM After Nutritive andOxidative Stress

It is also possible to evaluate the autophagy of stressed cutaneouscells by visualizing the expression of the protein DRAM by WesternBlott.

The evaluation of the expression of DRAM was therefore analyzed underthese moderate stress conditions with 125 μM of H₂O₂ on HaCaTkeratinocyte cultures and on normal human keratinocytes. The expressionof DRAM is presented in the table below in percentage relative to thecontrol (without stress).

Recovery Time (Hours) Expression of DRAM (%) Without Stress 2 100 H₂O₂,125 μM 0.5 120 1 180 1.5 390 2 200

It is noted that a nutritive and oxidative stress on the cutaneous cellcultures increase the expression of the protein DRAM.

For the 125 μM dose of oxidative stress, it is observed that the markingof the protein DRAM is at its maximum after 1.5 hours of recovery, andthen it is minimized starting from 2 hours.

The conditions of nutritive and oxidative stress therefore make itpossible to induce an autophagic-type phenomenon.

These studies have therefore made it possible to show that the autophagymechanism can be visualized on cutaneous cell cultures that are stressedby the evaluation of the expression of different proteins such asMAP-LC3, the phosphorylated protein p53, or the protein DRAM.

3/Comparison of the Autophagy in Young or Aged Cells

This study has as its objective to compare the autophagy level of youngcells (from donors with a mean age of 26 years) and aged cells (fromdonors with a mean age of 70 years) that are subjected to the sameoxidative and nutritive stresses.

The evaluation of the autophagy level was considered by the analysis ofthe expression of the protein MAP-LC3 by Western Blott.

The protocol that is put into place is as follows:

-   -   Cultures of so-called young or aged cells for 24 hours in the        complete culture medium,    -   Removal of the complete culture medium, replacement with the        non-nutritive culture medium that contains the oxidizing agent        H₂O₂ for 3 hours at different doses,    -   Removal of the oxidizing agent, replacement by the complete        culture medium without an oxidizing agent,    -   Evaluation of the expression of MAP-LC3 after cellular recovery.

The results are described in the table below in percentage relative tothe control (without stress).

Expression of MAP-LC3 On Young Cells On Aged Cells Without Stress 100100 H₂O₂, 125 μM 172 138 H₂O₂, 250 μM 322 187 H₂O₂, 400 μM 168 135 H₂O₂,600 μM 143 96 H₂O₂, 1000 μM 117 92

Under the conditions of this study, the so-called young cutaneous cellsshow an increase of the expression of MAP-LC3 when they are subjected toa moderate oxidative stress (125, 250, see 400 μM). When they aresubjected to a significant oxidative stress (600 and 1,000 μM), they areplaced in apoptosis.

The so-called aged cutaneous cells do not have the same increase of theexpression MAP-LC3 when they are subjected to the same moderateoxidative stress.

This difference in the way that aged cells were put into autophagycompared to the young cells is significant.

This study therefore shows that aged cells are no longer capable ofbeing protected and of detoxifying during a moderate nutritive andoxidative stress.

4/Screening of Active Ingredients Increasing the Autophagy of CutaneousCells

The screening is executed according to the protocol of nutritive andoxidative stress presented in Item 2.1, starting from active ingredientsoriginating from plants, algae or yeasts. The evaluation of the effectof active ingredients on the autophagy of cutaneous cells has beencarried out by analyzing the expression of the protein MAP-LC3 incutaneous cell cultures subjected to a nutritive and oxidative stress.

The protocol of the test is as follows:

-   -   Cultivations of cells for 24 hours in a complete culture medium,    -   Removal of the complete culture medium, replacement with the        non-nutritive culture medium that contains the oxidizing agent        H2O2 for 3 hours that may or may not be in the presence of        active ingredients,    -   Removal of the oxidizing agent and the non-nutritive culture        medium, replacement by the complete culture medium that may or        may not be in the presence of the active ingredients,    -   Evaluation of the expression of MAP-LC3 after cellular recovery        by immunofluorescent marking.

The tested active ingredients have been produced according to thefollowing protocol:

-   -   Solubilization of plant, algae or yeast powder in water at a        rate of 50 g/l (m/v),    -   Enzymatic hydrolysis,    -   Separation of soluble and insoluble phases,    -   Filtration and sterilizing filtration.

The primary active ingredients are:

Plants or Yeasts Active Ingredient that are Used Active ingredientoriginating from Lithothamnium calcareum Lithothamnium Active ingredientoriginating from Melilot Melilotus officinalis Active ingredientoriginating from lemon Citrus limonum Active ingredient originating fromCandida Candida saitoana saitoana Active ingredient originating fromlentils Lens culinaris Active ingredient originating from stingingUrtica dioica nettles Active ingredient originating from Averrhoacarambola carambola Active ingredient originating from Momordicacharantia momordica Active ingredient originating from Yarrowialipolytica Yarrowia lipolytica

The results of the most effective active ingredients that are selectedand tested in triplicate are described in the following table:

Expression of MAP-LC3 Without active ingredient ± Active ingredientoriginating from +++ Lithothamnium Active ingredient originating fromMelilot ++ Active ingredient originating from lemon ++ Active ingredientoriginating from Candida ++ saitoana Active ingredient originating fromlentils + Active ingredient originating from + stinging nettles Activeingredient originating from carambola + Active ingredient originatingfrom momordica + Active ingredient originating from Yarrowia +lipolytica

These active ingredients therefore make it possible to increase theautophagy of cutaneous cells that are subjected to a moderate nutritiveand oxidative stress and thus to detoxify the skin and to prevent orcombat the cutaneous aging.

These active ingredients can be incorporated in cosmetic compositions.

5. Examples of Cosmetic Compositions that Contain an Active Ingredientthat Acts on the Autophagy of Cutaneous Cells

The invention also covers the cosmetic compositions, including at leastone active ingredient that acts on the autophagy of cutaneous cells indifferent galenical forms, suitable for administration by cutaneoustopical means.

These compositions can come in particular in the form of creams,oil-in-water emulsions, water-in-oil emulsions, multiple emulsions,solutions, suspensions or powders. They can be more or less fluid andhave the appearance of a cream, a lotion, a milk, a serum, an ointment,a gel, a paste or a foam, or in solid form.

These compositions contain between 0.01 and 15% by weight of activeingredient(s) acting on the autophagy of cutaneous cells according tothis invention, preferably between 1% and 4%.

5.1. Expert Cream

An example of a cream that comprises an active ingredient that isextracted from lemon, as presented in Item 4, can have the followingcomposition:

A. Water Enough to produce 100% Glycerol (Univar) 3.33% EDTA 0.13%Satialgine (Degussa) 0.66% Talc (Luzenac)   1% B. Miglyol 812 (CondeaChemie) 3.33% Ritaphyl ICS (Rita) 1.33% Ritachol SS (Rita) 1.33% Ipm(Univar) 3.33% Ritalan C (Rita) 1.33% Montanov 14 (Seppic) 1.33% Lanol14M (Seppic) 1.33% Brij 72 (Uniquema)   1% Brij 721 (Uniquema) 0.33% C.Phenoxyethanol (Sigma)  0.9% Ethylhexylglycerin (Seppic)  0.1% D. Activeingredient originating from lemon   4% according to the invention

The cream is obtained by the execution of the following stages:

-   -   Heating A and B to 80° C., while being stirred mechanically,    -   Emulsifying B in A while being stirred,    -   At 30° C., adding C in order, and    -   Continuing the homogenization until the cream is uniform.

5.2 Anti-Wrinkle Cream

An example of a cream that comprises an active ingredient that isextracted from lithothamnium, as presented in Item 4, can have thefollowing composition:

A. Water Enough to produce 100% Butylene glycol (Univar) 3% B.Isohexadecane (Laserson) 5% Rita IPP (Rita) 2% Montanov 202 (Seppic) 3%Arlacel 161 (Uniquema) 1% Ritox 59 (Rita) 1% Lanette O (Cognis) 1% C.Phenoxyethanol (Sigma) 0.9%   Ethylhexylglycerin (Seppic) 0.1%   DC 200(Dow Corning) 0.5%   Active ingredient originating from 4% Lithothamniumaccording to the invention D. Sepigel 305 (Seppic) 4%

The cream is obtained by the execution of the following stages:

-   -   Mixing A, mixing B, and heating A and B to 80° C., while being        stirred mechanically,    -   Emulsifying B in A while being stirred,    -   At 30° C., adding C in order, and    -   Continuing the homogenization until the cream is uniform.

5.3 Night Cream

An example of a cream that comprises an active ingredient that isextracted from Melilothus, as presented in Item 4, can have thefollowing composition:

A. Water Enough to produce 100% Carbopol ETD 2020 (Noveon) 0.4% B. Cetylalcohol (Stearinerie Dubois)   3% Stearyl alcohol (Stearinerie Dubois)  3% DUB MCT 5545 (Stearinerie Dubois) 4.5% DC 345 (Dow Corning) 7.5%Monomuls 900 18 (Henkel)   3% C. Phenoxyethanol (Sigma) 0.9%Ethylhexylglycerin (Seppic) 0.1% Active ingredient that originates from  4% Melilotus according to the invention D. NaOH Enough to produce pH4.5

The cream is obtained by the execution of the following stages:

-   -   Mixing A, thoroughly dispersing the gel and mixing B,    -   Heating A and B to 80° C.,    -   Emulsifying B in A while being stirred,    -   At 40° C., adding C in order,    -   Continuing the homogenization until the cream is uniform,    -   Adjusting the pH with D, and    -   Allowing it to cool to 30° C. while being stirred.

5.4 Cream for Mature Skin

An example of cream that comprises an active ingredient that isextracted from Candida saitoana, as presented in Item 4, can have thefollowing composition:

A. Water Enough to produce 100% Glycerol (Univar) 1.75%  Propyleneglycol (Univar) 6.5% Aculyne 33A (ISP) 2.5% Carbopol EDT 2020 (Goodrich)0.5% B. Cetiol SN (Cognis)   3% Eumulgine B1 (Cognis) 1.75%  RitaphylICS (Rita)   3% Patlac IL (Rita)   3% Isopropyl myristat (Univar)   3%Montane 80 (Seppic) 1.5% Montanox 60 (Seppic) 1.5% DC 345 (Dow Corning)  3% C. Phenoxyethanol (Sigma) 0.9% Ethylhexylglycerin (Seppic) 0.1% D.Active ingredient that originates from   4% Candida saitoana NaOH Enoughto produce pH 5.5

The cream is obtained by the execution of the following stages:

-   -   Mixing A, mixing B, and heating A and B to 80° C.,    -   Emulsifying B in A while being stirred,    -   At 30° C., adding C and D,    -   Adjusting to pH 5.5 with NaOH, and    -   Continuing homogenization until the cream is uniform.

1. Cosmetic process for detoxifying the skin and/or for preventingand/or combating cutaneous aging, comprising the topical application onthe skin of a composition that comprises at least one activator of theautophagy of cells of the skin.